This application claims the priority of Korean Patent Application No. 2003-66949, filed on Sep. 26, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention related to a cathode composition for lithium secondary battery and a method of preparing the same, particularly, related to the cathode composition consists of lithium-chromium-titanium-manganese oxides with layered α-LiFeO2 structure.
2. Description of the Related Art
There have been considerable works on substituting Mn4+ in Li2MnO3 with Ni, Co, Cr, or Ti partially in the development of cathode materials for lithium batteries, as disclosed in U.S. Patent Publication No. 2002/0114995 A1. However, those manganese-based layered oxides exhibited insufficient capacity for commercialization, for example, xLi2TiO3.(1−x)LiNi0.5Mn0.5O2 (x≦0.1) prepared by conventional method showed only 140 mAh/g capacity.
Recently, the synthesis of a novel lithium-nickel-manganese oxide, xLiNiO2.(1−x)Li2MnO3, with a high capacity of 230 mAh/g disclosed in U.S. Patent Publication No. 2003/0027048 A1. However, the material exhibited a wide range of discharge voltage, from 4.6 to 3.0 V, which may result in voltage fluctuation when it was used commercially. On the other hand, xLiNiO2.(1−x)Li2MO3 (M=Mn or Ti, ⅓≦x≦½) material that was reported to have possible application in secondary lithium battery is too expensive to use due to the high cost of Ni.